as it is a 14sb, it has a kawasaki engine on it. when you push the throttle lever all the way forward, check to make sure the choke linkage is closing all the way on the carb. if not, pull the lever back to the fast position and see if 2 holes line up on the plate the cable hooks to. this is the throttle plate. if the holes don't line up, loosen the cable retaining screw and move the cable to align the holes. like tomplum says, fresh fuel helps. also, don't forget to check spark.

The 2 stroke was a sweeter machine, but the 4 stroke model still gives you what you want...superior side discharge, aluminum deck, and self propelled. Most mowers made today are "crappy" side dischargers. Side discharging is not really popular anymore, the the most you typically get is an oval opening on the side of the deck (garbage design). I love my LB for side discharging, I can effectively mow down the highest of grasses in my yard in several areas I only mow once or twice a season, and this is very much because the side discharge LB can really shoot out the clipping. As TPA mentioned...the design here is key, the discharge is at a tangent to the deck, giving it the highest velocity over other mowers. Here is a link that might be useful: New LB

The Briggs OHV mower engine was introduced about 10 years ago. It features the same displacement, bore & stroke as the Quantum series engine. The engine is several pounds heavier than the Quantum series.The carburetor is easy to service - but not quite as easy as the Quantum. The throttle plate does not have a stop screw for the idle position as the engine is designed for governed slow speed. The throttle plate wedged in the closed position on the engine I have - even tho the throttle control was set for full speed. This created some hard starts until I discovered what was happening. A boss was provided so I installed my own throttle stop screw. At my 7300 foot altitude, the compression release reduces the starting compression to about 30 - 40 psi. Normally, the engine started ok. Power was very good. The cast iron sleeve is a good feature. The mower deck is similar to the Snapper design. Previously the comments on this board seemed to favor the Toro Super Recyler as the best mulcher mower. The Snapper design was good for bagging (the model in the link you provided is set up for mulching). Rear drive is a good feature. The caster wheel design adds a few more pounds to the overall weight of this mower. Since the mower was returned, is there a warranty? Does John Deere honor the warranty on returned equipment? $300 is probably a good price provided you like the mower. My opinion - Before buying, look at the JS-20 for the following reasons. The engine is the older flat head design and weighs less. This Quantum series engine is equipped with the "ready start" system that (in my opinion) is easier to start than any other brand engine including the OHV Briggs on the JS40 The mower has the regular front wheels - not the caster style. Here is a Gee Whiz point. I don't think any of the other mower manufacturers use the cast iron sleeve Briggs as the aluminum version is cheaper. Most of the Honda mowers use the aluminum bore Honda engine. I believe all Kawasaki engines are equipped with cast iron sleeves.

The majority of the time new mowers run at too slow of an RPM - even 200-300 rpms below the conservative settings that many shops use as a guideline. Deere has a regular and a mulch blade available, but maybe a Snapper dealer could turn you on to something that works better.